Micro-connection structure and manufacturing method thereof

ABSTRACT

A micro-connection structure is provided. The micro-connection structure includes an under bump metallurgy (UBM) pad, a bump and an insulating ring. The UBM pad is electrically connected to at least one metallic contact of a substrate. The bump is disposed on the UBM pad and electrically connected with the UBM pad. The insulating ring surrounds the bump and the UBM pad. The bump is separate from the insulating ring with a distance and the bump is isolated by a gap between the insulating ring and the bump.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of U.S. patent application Ser. No. 15/841,336, filedDec. 14, 2017 and now pending, and claims the priority benefit of U.S.provisional application Ser. No. 62/581,788, filed on Nov. 6, 2017. Theentirety of the above-mentioned patent applications is herebyincorporated by reference herein and made a part of this specification.

BACKGROUND

Micro-bump technologies are able to provide a higher input/outputdensity within the smaller form factor packages with acceptableelectrical performance. Even though the development of fine-pitchmicro-bump packages faces quite a few challenges, further solutions areproposed to enhance the bonding strength and the reliability of themicro-connections.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A to FIG. 1J′ are schematic cross-sectional views showing aportion of an exemplary package at various stages of the manufacturingmethod for forming at least one micro-connection structure in thepackage according to some embodiments of the present disclosure.

FIG. 1K and FIG. 1K′ are schematic top views showing a portion of anexemplary package similar to the structures shown in FIG. 1J and FIG.1J′ respectively.

FIG. 2A to FIG. 2H are schematic cross-sectional views showing a portionof an exemplary package at various stages of the manufacturing methodfor forming at least one micro-connection structure in the packageaccording to some embodiments of the present disclosure.

FIG. 3A to FIG. 3G are schematic cross-sectional views showing a portionof an exemplary package at various stages of the manufacturing methodfor forming at least one micro-connection structure in the packageaccording to some embodiments of the present disclosure.

FIG. 4A is a schematic cross-sectional view of an exemplarymicro-connection structure of a package in accordance with someembodiments of the present disclosure.

FIG. 4B is a schematic three-dimensional view of an exemplarymicro-connection structure of a package in accordance with embodimentsof the present disclosure.

FIG. 5 is a schematic cross-sectional view of an exemplarymicro-connection structure of a package in accordance with someembodiments of the present disclosure.

FIG. 6 is a schematic cross-sectional view of an exemplarymicro-connection structure of a package in accordance with someembodiments of the present disclosure.

FIG. 7 is a schematic cross-sectional view of an exemplary packagehaving micro-connection structures in accordance with some embodimentsof the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The embodiments of the present disclosure describe the exemplarymanufacturing processes of semiconductor packages and the packagesfabricated there-from. Although the steps of the method are illustratedand described as a series of acts or events, it will be appreciated thatthe illustrated ordering of such acts or events are not to beinterpreted in a limiting sense. In addition, not all illustratedprocess or steps are required to implement one or more embodiments ofthe present disclosure. The embodiments are intended to provide furtherexplanations but are not used to limit the scope of the presentdisclosure.

FIG. 1A to FIG. 1J illustrates schematic cross-sectional views showing aportion of an exemplary package at various stages of the manufacturingmethod for forming at least one micro-connection structure in thepackage according to some embodiments of the present disclosure.Referring to FIG. 1A, in certain embodiments, a substrate 100 having atleast one metallic contact 102 therein is provided. In some embodiments,the substrate 100 is a monocrystalline semiconductor substrate, such asa bulk silicon substrate or a silicon wafer. In some embodiments, thesubstrate 100 may be a silicon-on-insulator (SOI) substrate or a GOI(germanium-on-insulator) substrate as alternatives. In certainembodiments, the substrate 100 includes a chip or a die and may be partof a wafer or a reconstructed wafer. Also, in accordance with theembodiments, the substrate 100 may include other conductive layers,doped regions or active devices (such as transistors, diodes or thelike) or other semiconductor elements. In some embodiments, thesubstrate 100 includes at least one semiconductor chip (or die) 101having a plurality of contact pads and the metallic contact 102 is oneof the contact pads of the semiconductor chip 101. Although thesubstrate 100 has more than one metallic contacts 102, only oneexemplary metallic contact is shown herein. In some embodiments, thematerial of the metallic contact 102 includes copper or copper alloys,for example.

As shown in FIG. 1A, a protection layer 104 is formed on the activesurface 100 a of the substrate 100, and a patterned insulating layer 106is formed on the protection layer 104. In some embodiments, theprotection layer 104 includes a silicon nitride layer. In alternativeembodiments, the protection layer 104 is optionally formed and may beskipped. In some embodiments, the formation of the patterned insulatinglayer 106 includes forming an insulating material layer (not shown) onthe protection layer 104 and then patterning the insulating materiallayer to form openings S1 exposing the underlying protection layer 104.In some embodiments, the material of the patterned insulating layer 106includes silicon oxide, silicon nitride, silicon oxynitride and/or thecombinations thereof. In some embodiments, the insulating material layerincludes a stack of a silicon nitride layer sandwiched between twosilicon oxide layers. In some embodiments, the protection layer 104 andthe insulating material layer may be formed by chemical vapor deposition(CVD). In one embodiment, the patterned insulating layer 106 may bepatterned into ring patterns that partially cover and surround themetallic contacts 102, with central openings S1 exposing the protectionlayer 104 on the metallic contacts 102. That is, the patternedinsulating layer 106 may be considered as a plurality of insulatingrings. In some embodiments, a barrier layer 108 is formed on thepatterned insulating layer 106 and the barrier layer 108 is conformal tothe profile of the opening S1 of the patterned insulating layer 106. Insome embodiments, the location of the opening S1 may correspond to thelocation of the metallic contact 102. In one embodiment, the opening S1is smaller in size than the metallic contact 102. The barrier layer 108covers the protection layer 104 exposed by the openings S1 of thepatterned insulating layer 106. Later, a filling layer 110 is formedover the barrier layer 108 and the patterned insulating layer 106,filling up the openings S1. In some embodiments, the material of thebarrier layer 108 includes metal oxide formed by physical vapordeposition (PVD) or CVD. In one embodiment, the barrier layer 108includes an aluminum oxide layer, for example. The barrier layer 108 ismore resistant to the following etching process. In one embodiment, thebarrier layer 108 functions to prevent the subsequent formed bump beingcontaminated due to diffusion of impurities from the underlyinglayer(s). In some embodiments, the filling layer 110 may include one ormore materials selected from tetraethyl orthosilicate (TEOS), siliconoxide, silicate glass and low dielectric constant materials. The methodof forming the filling layer 110 includes CVD, high aspect ratio process(HARP) or spin coating, for example.

In some embodiments, in FIG. 1B, a patterning process is performed toform a plurality of openings S2 exposing the underlying metallic contact102. In certain embodiments, the patterning process is performed byforming a photoresist pattern (not shown) on the filling layer 110 andperforming an etching process to partially remove the filling layer 110,the barrier layer 108 and the protection layer 104. In some embodiments,the location of the opening S2 may correspond to the location of themetallic contact 102. In some embodiments, the size of the opening S2 issmaller than the size of the opening S1, and the opening S2 is locatedwithin the opening S 1. In one embodiment, the opening S2 exposes acentral portion of the metallic contact 102, and the patternedinsulating layer 106 is covered by the barrier layer 108 but not exposedby the openings S2. In certain embodiments, the shape of the opening S2may be round, oval, rectangular or any polygonal shape. In oneembodiment, the opening S2 is in a round shape and the subsequentlyformed bump may be in an approximately round shape.

In FIG. 1C, a bonding enhancement layer 112 and a seed layer 114 areformed sequentially on the patterned filling layer 110 and on theexposed metallic contact 102. In some embodiments, the bondingenhancement layer 112 is formed over the patterned filling layer 110covering the top surface 110 a of the patterned filling layer 110 andcovering the bottom BS2 of the opening S2 (i.e. covering the exposedmetallic contact 102) and the sidewall(s) SS2 of the opening S2 (i.e.covering the exposed sides of the patterned filling layer 110, thebarrier layer 108 and the protection layer 104). That is, the bondingenhancement layer 112 is located directly on and in direct contact withthe metallic contact 102. In certain embodiments, depending on theaspect ratio, the bonding enhancement layer 112 formed on the metalliccontact 102 and on the top surface 110 a may be thicker than the bondingenhancement layer 112 formed on the sidewalls SS2. Later, the seed layer114 is conformally formed on the bonding enhancement layer 112. In someembodiments, the material of the bonding enhancement layer 112 includestitanium, tungsten, chromium, a titanium-tungsten alloy, atitanium-tungsten-copper alloy, a titanium-copper alloy or combinationsthereof. In one embodiment, the bonding enhancement layer 112 includes atitanium-tungsten (TiW) layer. In one embodiment, the bondingenhancement layer 112 may be formed with a thickness of about 2500˜4000angstroms or about 3000˜3200 angstroms by sputtering or physical vapordeposition (PVD). In some embodiments, the seed layer 114 includes agold layer formed by sputtering or PVD. In one embodiment, the seedlayer 114 is formed with a thickness of about 700˜900 angstroms or 800angstroms.

Referring to FIG. 1D, a masking layer 120 is formed over the substrate100 and on the seed layer 114, filling up the opening S2. In someembodiments, the masking layer 120 is a photoresist layer.

Referring to FIG. 1E, an etching back process is performed to remove themasking layer 120 outside the opening S2 and above the patterned fillinglayer 110 so that a masking pattern 121 is remained within the openingS2 with a top surface 121 a lower than the top surface 110 a of thepatterned filling layer 110. In some embodiments, the etching backprocess includes an anisotropic etching process.

In some embodiments, in FIG. 1F, using the masking pattern 121 as anetching mask, the bonding enhancement layer 112 and the seed layer 114are removed until the top surface 110 a of the patterned filling layer110 is exposed. In some embodiments, the bonding enhancement layer 112and the seed layer 114 outside the opening S2 and above the patternedfilling layer 110 are removed to form the bonding enhancement pattern113 and the seed pattern 115 respectively (i.e. the bonding enhancementlayer 112 and the seed layer 114 remained in the opening S2 andsurrounding the masking pattern 121). In certain embodiments, the topsof the bonding enhancement pattern 113 and the seed pattern 115 arelower than the top surface 121 a of the masking pattern 121. In oneembodiment, the tops of the bonding enhancement pattern 113 and the seedpattern 115 are lower than the barrier layer 108 located on the topsurface 106 a of the patterned insulating layer 106. In one embodiment,the bonding enhancement layer 112 and the seed layer 114 are removed byperforming at least a wet etching process.

Referring to FIG. 1G, the masking pattern 121 (see FIG. 1F) is removedand the bonding enhancement pattern 113 and the seed pattern 115 locatedwithin the opening S2 are exposed. In some embodiments, the maskingpattern 121 is removed by performing the photoresist stripping process.

Referring to FIG. 1H, portions of the bonding enhancement pattern 113and the seed pattern 115 located on the sidewalls SS2 of the opening S2are removed. In one embodiment, the bonding enhancement pattern 113 andthe seed pattern 115 located on the sidewalls SS2 are both removed, andthe remained seed pattern 115 a is surrounded by the remained bondingenhancement pattern 113 a but the remained seed pattern 115 a is not incontact with the sidewalls SS2. That is, the remained seed pattern 115 ais inlaid in the remained bonding enhancement pattern 113 a and issurrounded by a ring-shaped ridge portion 1131 of the remained bondingenhancement pattern 113 a. In some embodiments, the removal of thebonding enhancement pattern 113 and the seed pattern 115 located on thesidewalls SS2 of the opening S2 includes performing a wet etchingprocess or a lateral etching process, which especially removes thebonding enhancement pattern 113 and the seed pattern 115 on the verticalside surfaces SS2, instead of those on the horizontal surfaces (i.e.surfaces parallel to the active surface 100 a). In one embodiment, thewet etching process includes a first wet etching process for gold and asecond wet etching process for titanium-tungsten. In certain cases, inthe presence of another metal (such as Ti or TiW), a vertical orreentrant profile with much greater undercut is often observed duringwet etching a gold film with an underlying adhesion layer of anothermetal. In one embodiment, the bonding enhancement pattern 113 and theseed pattern 115 located on the sidewalls SS2 are removed until theremained seed pattern 115 a is levelled with the remained bondingenhancement pattern 113 a. That is, the top surface 115S of the remainedseed pattern 115 a is horizontally flush with the top surface of theridge portion 1131. In one embodiment, the top surface 115S of theremained seed pattern 115 a is higher than the barrier layer 108 locatedon the protection layer 104. In some embodiments, the remained bondingenhancement pattern 113 a and the remained seed pattern 115 a located onthe bottom BS2 of the opening S2 may function as an under bumpmetallurgy (UBM) pad 117. In some embodiments, the stack of the remainedbonding enhancement pattern 113 a and the remained seed pattern 115 a(the UBM pad 117) has a height H1. In some embodiments, the height H1ranges from about 500 angstroms to about 3000 angstroms.

As shown in FIG. 1I, a plurality of bumps 130 (only one is shown) isformed on the remained seed pattern 115 a and the remained bondingenhancement pattern 113 a within the opening S2. In some embodiments,the material of the bump includes gold formed by electroless plating. Incertain embodiments, the bumps 130 are directly formed on the remainedseed pattern 115 a using the gold pattern as the seed layer duringelectroless plating. In one embodiment, the bump 130 is a gold bump orgold stud bump. In one embodiment, the bump 130 has a top surface 130 alower than the top surface 110 a of the patterned filling layer 110, buthigher than the barrier layer 108 located on the top surface 106 a ofthe patterned insulating layer 106. In some embodiments, the bumps 130have a height H2. In some embodiments, the bump 130 sits on the remainedseed pattern 115 a with the ridge portion 1131 surrounding the bump 130.If considering the bump 130 being a round bump, the diameter (size) ofthe bump 130 may be equivalent to or less than 3.5 microns or may rangefrom about 1.5 microns to about 3.5 microns.

In some embodiments, as the bonding enhancement layer 112 and the seedlayer 114 are removed before the formation of the bumps 130, thesubsequently formed bumps 130 can provide a pure metal joint surface forfurther bonding and will not be affected or polluted by possibleparticles or residues resulted from UBM etching.

Referring to FIG. 1J, the patterned filling layer 110 is removed and thebarrier layer 108 is exposed. In certain embodiments, the exposedbarrier layer 108 located on the patterned insulating layer 106 coversthe top surface 106 a and sidewalls SS1 (i.e. the sidewalls SS1 of theopening S1) of the patterned insulating layer 106 as well as theprotection layer 104 exposed by the openings S1 of the patternedinsulating layer 106. Due to the existence of the patterned insulatinglayer 106, the barrier layer 108 has a step height difference SH. Insome embodiments, the top surface 130 a of the bump 130 is higher thanthe top surface 108 a of the barrier layer 108 located on the topsurface 106 a of the patterned insulating layer 106. In one embodiment,as shown in FIG. 1J, the barrier layer 108 located on the protectionlayer 104 is in direct contact with the remained bonding enhancementpattern 113 a but is not in contact with the bump 130 or the remainedseed pattern 115 a.

As seen in FIG. 1J and 1K, there is a gap (empty space) G between thebump 130 and the barrier layer 108 located on the sidewalls SS1. Incertain embodiments, the gap G provides room for accommodating extrabonding material during the bonding of the gold bump with externalconnections, thus avoiding shorts and improving the connectionreliability. In some embodiments, the bump 130 is surrounded by thebarrier layer 108 but is not in contact with the barrier layer 108. Thatis, the bump 130 is isolated and separated by the ring-shaped gap Gsurrounding the bump 130 and the bump 130 is separated from the barrierlayer 108 on the sidewall SS1 with a distance dl. From the top view ofFIG. 1K, the span of the gap G is shown by the dotted line, and thebumps 130 are surrounded by the barrier layer 108. In FIG. 1K, two bumps130 are shown, but it is understood that the number of the bumps is notlimited by the embodiments herein. In some embodiments, the total height(H1+H2) of the bump 130 and the UBM pad 117 (the stack of the remainedbonding enhancement pattern 113 a and the remained seed pattern 115 a)is larger (higher) than the step height SH. In some embodiments, thetotal height (H1+H2) of the bump 130 and the UBM pad 117 is larger thanthe sum of the thickness of the protection layer 104 and the step heightSH. That is, the bump 130 located on the UBM pad 117 protrudes out ofthe opening S1 and is higher than the barrier layer 108. In someembodiments, the total height (H1+H2) of the bump 130 and the UBM pad117 ranges from about 0.5 microns to about 1.4 microns. In someembodiments, the size d1 (i.e. the largest distance between the bumpsidewall and the barrier layer 108 located on the sidewall SS1 of theopening S1) of the gap G ranges from 0.2 microns to about 1.5 microns.

FIG. 1H′, FIG. 1I′ and FIG. 1J′ are schematic cross-sectional viewsshowing a portion of an exemplary package at various stages of themanufacturing method for forming at least one micro-connection structurein the package according to alternative embodiments of the presentdisclosure. In alternative embodiments, referring to FIG. 1H′, followingthe processes as described in FIG. 1A to FIG. 1G, sidewall/verticalportion of the seed pattern 115 (the seed pattern 115 located on thesidewalls SS2 of the opening S2) is removed while the sidewall portion1133 of the bonding enhancement pattern 113 (the bonding enhancementpattern 113 located directly on the sidewalls SS2 of the opening S2) isnot removed. In one embodiment, the remained seed pattern 115 a locatedwithin the bonding enhancement pattern 113 is not in contact with thesidewalls SS2. That is, the remained seed pattern 115 a is disposed onthe bonding enhancement pattern 113 and is surrounded by the ring-shapedsidewall portion 1133 of the bonding enhancement pattern 113. In someembodiments, the removal of the seed pattern 115 located on thesidewalls SS2 of the opening S2 includes performing a wet etchingprocess or a lateral etching process, which especially removes the seedpattern 115 on the vertical side surfaces SS2, instead of those on thehorizontal surfaces (i.e. surfaces parallel to the active surface 100a). In one embodiment, the top of the sidewall potion 1133 of thebonding enhancement pattern 113 is lower than the barrier layer 108located on the top surface 106 a of the patterned insulating layer 106.In some embodiments, the top surface 115S of the remained seed pattern115 a is higher than the barrier layer 108 located on the protectionlayer 104. In some embodiments, the bonding enhancement pattern 113 andthe remained seed pattern 115 a may function as an under bump metallurgy(UBM) pad 117′. Compared with the UBM pad 117 depicted in FIG. 1H, theUBM pad 117′ in FIG. 1H′ has extra (unremoved) sidewall portion 1133. Insome embodiments, the sidewall portion 1133 has a height H3 and theremained seed pattern 115 a and the bottom portion of the bondingenhancement pattern 113 has a height H1.

As shown in FIG. 1F, a plurality of bumps 130 (only one is shown) isformed on the remained seed pattern 115 a, within the bondingenhancement pattern 113 and within the opening S2. In some embodiments,the material of the bump 130 includes gold formed by electrolessplating. In one embodiment, the bump 130 is a gold bump or gold studbump. In one embodiment, the bump 130 has a top surface 130 a lower thanthe top surface 110 a of the patterned filling layer 110. In someembodiments, the bumps 130 have a height H2, and the height H3 of thesidewall portion 1133 is at least larger than 1/10 of the total height(H1+H2) of the bump 130 and the UBM pad 117′ and smaller than ½ of thetotal height (H1+H2) of the bump 130 and the UBM pad 117′. In someembodiments, the bump 130 sits on the remained seed pattern 115 a withthe sidewall portion 1133 surrounding the bump 130. In one embodiment,the unremoved sidewall portion 1133 covers a lower portion of thesidewall 130S of the bump 130.

Referring to FIG. 1J′, the patterned filling layer 110 is removed andthe barrier layer 108 is exposed. In certain embodiments, the exposedbarrier layer 108 located on the patterned insulating layer 106 coversthe top surface 106 a and sidewalls SS1 (i.e. the sidewalls SS1 of theopening S1) of the patterned insulating layer 106 as well as theprotection layer 104 exposed by the openings S1 of the patternedinsulating layer 106. In some embodiments, the top surface 130 a of thebump 130 is higher than the top surface 108 a of the barrier layer 108located on the top surface 106 a of the patterned insulating layer 106.In one embodiment, as shown in FIG. 1J′, the bump 130 or the remainedseed pattern 115 a is not in contact with the barrier layer 108.

As seen in FIG. 1J′ and 1K′, there is a gap (empty space) G between thebarrier layer 108 located on the sidewalls SS1 and the bump 130 and thesidewall portion 1133. In certain embodiments, the gap G helps improvingthe connection reliability. In some embodiments, the bump 130 issurrounded by the barrier layer 108 but is not in contact with thebarrier layer 108. That is, the bump 130 is isolated by the gap G andthe sidewall portion 1133, and the bump 130 is separated from thebarrier layer 108 by a distance dl (i.e. the largest distance). From thetop view of FIG. 1K′, the bumps 130 are surrounded by the sidewallportion 1133 of the bonding enhancement pattern 113 and are surroundedby the barrier layer 108, while the spans of the gaps G are shown by thedotted lines. In some embodiments, the total height (H1+H2) of the bump130 and the UBM pad 117′ is larger than the step height SH. In someembodiments, the total height (H1+H2) of the bump 130 and the UBM pad117 is larger than the sum of the thickness of the protection layer 104and the step height SH. In some embodiments, the size d1 (the largestdistance between the bump sidewall and the barrier layer 108 located onthe sidewall SS1 of the opening S1) of the ring-shaped gap G ranges from0.2 microns to about 1.5 microns.

FIG. 4A is a schematic cross-sectional view of an exemplarymicro-connection structure of a package in accordance with someembodiments of the present disclosure. FIG. 4B is a schematicthree-dimensional view of an exemplary micro-connection structure of apackage in accordance with embodiments of the present disclosure. Asshown in FIG. 4A, in certain embodiments, the micron-connectionstructure 40 includes the UBM pad 117′, the bump 130, the patternedinsulating layer 106 and the barrier layer 108. In some embodiments, thebump 130 and the UBM pad 117′ are located on the metallic contact 102and electrically connected with the metallic contact 102. In someembodiments, the bump 130 located on the UBM pad 117′ protrudes out ofthe opening S1 and the bump 130 is higher than the barrier layer 108located on the patterned insulating layer 106. In some embodiments, thebump 130 sits on the remained seed pattern 115 a with the sidewallportion 1133 surrounding the bump 130. In some embodiments, the bump 130is surrounded and partially shielded by the sidewall portion 1133 andthe sidewall portion 1133 partially covers the sidewall 130S of the bump130. In some embodiments, in FIG. 4A and FIG. 4B, the patternedinsulating layer 106 may be patterned as rectangular ring-shaped patternor rectangular ring(s) and the barrier layer 108 covering therectangular ring-shaped patterned insulating layer 106 is shown as aprotruded rectangular ring(s). Herein, the insulating ring or thering-shaped patterns may be round, oval, rectangular or any suitablepolygonal rings. In FIG. 4B, the ring-shaped gap G surrounding the bump130 isolates the bump 130 from the protruded rectangular ring 108R (thebarrier layer 108 covering the rectangular ring-shaped patternedinsulating layer 106). In FIG. 4A, the barrier layer 108 is not inphysical contact with the bump 130, but the barrier layer 108 touchesthe UBM pad 117′. In some embodiments, the bump 130 has a height H2, andthe total height (H1+H2) of the bump 130 and the UBM pad 117′ rangesfrom about 0.5 microns to about 1.4 microns. In some embodiments, theheight H3 of the sidewall portion 1133 is at least larger than 1/10 ofthe total height (H1+H2) of the bump 130 and the UBM pad 117′ andsmaller than ½ of the total height (H1+H2) of the bump 130 and the UBMpad 117′.

FIG. 2A to FIG. 2H are schematic cross-sectional views showing a portionof an exemplary package at various stages of the manufacturing methodfor forming at least one micro-connection structure in the packageaccording to some embodiments of the present disclosure. The similar orsubstantially the same elements as described in FIG. 1A-FIG. 1K′ may belabelled with the same reference. The technology, process details,conditions or the materials used in the similar or substantially thesame manufacturing process will not be repeated or described in detailsin the following paragraphs.

Referring to FIG. 2A, in certain embodiments, the substrate 100 includesplural semiconductor chip or die 101 having more than one metalliccontact 102 is one of the contact pads of the semiconductor chip 101. Insome embodiments, the material of the metallic contact 102 includescopper or copper alloys, for example. In some embodiments, an optionalprotection layer 104 is formed on the active surface 100 a of thesubstrate 100, and a patterned insulating layer 106 is formed on theprotection layer 104. In some embodiments, there are openings S1 (one isshown) in the patterned insulating layer 106 exposing the protectionlayer 104. In one embodiment, the patterned insulating layer 106 may bepatterned into ring patterns that partially cover and surround themetallic contacts 102, with central openings S1 exposing the protectionlayer 104 on the metallic contacts 102. That is, the patternedinsulating layer 106 may be considered as a plurality of insulatingrings. Following the formation of a conformal barrier layer 108 and theformation of the filling layer 110, more than one opening S2 (one isshown) are formed exposing the metallic contact(s) 102. In someembodiments, the location of the opening S2 corresponds to the locationof the metallic contact 102, and the opening S2 exposes a centralportion of the metallic contact 102. Later, a metallic pad 109 is formedon the bottom BS2 of the opening S2 and is formed within the opening S2.In one embodiment, the metallic pad 109 has a height H4. In someembodiments, the material of the metallic pad 108 includes copper. Insome embodiments, the metallic pad 108 is a copper pad formed byelectroless plating, and the copper pad includes little impurity (e.g.less than or at most 100˜1000 ppm phosphorus (P) impurity).

In some embodiments, the material of the patterned insulating layer 106includes silicon oxide, silicon nitride, silicon oxynitride and/or thecombinations thereof. In one embodiment, the barrier layer 108 includesan aluminum oxide layer, for example. The barrier layer 108 is moreresistant to the following etching process. In one embodiment, thebarrier layer 108 functions to prevent the subsequent formed bump beingcontaminated due to diffusion of impurities from the underlyinglayer(s). In some embodiments, the filling layer 110 may include one ormore materials selected from tetraethyl orthosilicate (TEOS), siliconoxide, silicate glass and low dielectric constant materials. The methodof forming the filling layer 110 includes CVD, high aspect ratio process(HARP) or spin coating, for example.

In FIG. 2B, a bonding enhancement layer 112 and a seed layer 114 areformed sequentially on the patterned filling layer 110, covering theopening S2 and on the metallic pad 109. In some embodiments, the bondingenhancement layer 112 is formed over the patterned filling layer 110covering the top surface 110 a of the patterned filling layer 110, thetop surface 109 a of the metallic pad 109 and partially covering thesidewalls SS2 of the opening S2. That is, the bonding enhancement layer112 is located directly on and in direct contact with the metallic pad109. In certain embodiments, depending on the aspect ratio, the bondingenhancement layer 112 formed on the metallic pad 109 and on the topsurface 110 a may be thicker than the bonding enhancement layer 112formed on the sidewalls SS2. Later, the seed layer 114 is conformallyformed on the bonding enhancement layer 112. In some embodiments, thematerial of the bonding enhancement layer 112 includes titanium,tungsten, chromium, a titanium-tungsten alloy, atitanium-tungsten-copper alloy, a titanium-copper alloy or combinationsthereof. In one embodiment, the bonding enhancement layer 112 includes atitanium-tungsten (TiW) layer. In some embodiments, the seed layer 114includes a gold layer formed by sputtering or PVD.

Referring to FIG. 2C, a masking layer 120 is formed over the substrate100 and on the seed layer 114, filling up the opening S2.

Referring to FIG. 2D, an etching back process is performed to remove themasking layer 120 outside the opening S2 and above the patterned fillinglayer 110 so that a masking pattern 121 is remained within the openingS2 with a top surface 121 a lower than the top surface 110 a of thepatterned filling layer 110.

In some embodiments, in FIG. 2E, using the masking pattern 121 as anetching mask, the bonding enhancement layer 112 and the seed layer 114outside the opening S2 and above the patterned filling layer 110 areremoved to form the bonding enhancement pattern 113 and the seed pattern115 respectively (i.e. the bonding enhancement layer 112 and the seedlayer 114 remained in the opening S2 and surrounding the masking pattern121). In certain embodiments, the tops of the bonding enhancementpattern 113 and the seed pattern 115 are levelled or slightly lower thanthe top surface 121 a of the masking pattern 121. In one embodiment, thetops of the bonding enhancement pattern 113 and the seed pattern 115 arelower than the barrier layer 108 located on the top surface 106 a of thepatterned insulating layer 106. In one embodiment, the bondingenhancement layer 112 and the seed layer 114 are removed by performingat least a wet etching process.

Referring to FIG. 2F, the masking pattern 121 (see FIG. 2E) is removedand the bonding enhancement pattern 113 and the seed pattern 115 locatedwithin the opening S2 are exposed.

Referring to FIG. 2G, in some embodiments, the bonding enhancementpattern 113 and the seed pattern 115 located on the sidewalls SS2 areboth removed. In some embodiments, the remained seed pattern 115 a issurrounded by the remained bonding enhancement pattern 113 a but theremained seed pattern 115 a is not in contact with the sidewalls SS2.That is, the remained seed pattern 115 a is surrounded by a ring-shapedridge portion 1131 of the remained bonding enhancement pattern 113 a. Insome embodiments, the removal of the bonding enhancement pattern 113 andthe seed pattern 115 located on the sidewalls SS2 of the opening S2includes performing a wet etching process or a lateral etching process,which especially removes the bonding enhancement pattern 113 and theseed pattern 115 on the vertical side surfaces SS2, instead of those onthe horizontal surfaces (i.e. surfaces parallel to the active surface100 a). For the bonding enhancement pattern 113 and the seed pattern 115located on the sidewalls SS2 of the opening S2, they can be partiallyremoved or mostly removed, depending on the etching reaction time of theetching process. In one embodiment, the top surface 115S of the remainedseed pattern 115 a is horizontally flush with the top surface of theridge portion 1131. In one embodiment, the top surface 115S of theremained seed pattern 115 a is lower than the barrier layer 108 locatedon the patterned insulating layer 106. In some embodiments, the remainedbonding enhancement pattern 113 a and the remained seed pattern 115 alocated within the opening S2 may function as an under bump metallurgy(UBM) pad 117. In some embodiments, the stack of the remained bondingenhancement pattern 113 a and the remained seed pattern 115 a (the UBMpad 117) has a height H5. In some embodiments, the height H5 ranges fromabout 500 angstroms to about 3000 angstroms.

As shown in FIG. 2H, a plurality of bumps 130 (only one is shown) isformed within the opening S2. In some embodiments, the material of thebumps 130 includes gold formed by electroless plating. In certainembodiments, the bumps 130 are directly formed on the remained seedpattern 115 a using the gold pattern as the seed layer duringelectroless plating. In some embodiments, the bumps 130 have a heightH6. In some embodiments, the bump 130 sits on the remained seed pattern115 a with the ridge portion 1131 surrounding the bump 130. Later, thepatterned filling layer 110 is removed to expose the barrier layer 108.In certain embodiments, the barrier layer 108 covers the top surface 106a and sidewalls SS1 of the patterned insulating layer 106 as well as theprotection layer 104 exposed by the openings S1 of the patternedinsulating layer 106. Due to the existence of the patterned insulatinglayer 106, the barrier layer 108 has a step height difference SH. In oneembodiment, as shown in FIG. 2H, the barrier layer 108 located on theprotection layer 104 is in direct contact with the metallic pad 109 butis not in contact with the bump 130 or the UBM pad 117. In someembodiments, there is a gap (empty space) G between the bump 130 and thebarrier layer 108 located on the sidewalls SS1. In certain embodiments,the gap G provides room for accommodating extra bonding material duringthe bonding of the gold bump with external connections, thus avoidingshorts and improving the connection reliability. The bump 130 and theUBM pad 117 are isolated by the gap G and are separated from the barrierlayer 108 and the patterned insulating layer 106 by the ring-shaped gapG surrounding the bump 130 and the UBM pad 117. In some embodiments, thetotal height (H4+H5+H6) of the metallic pad 109, the UBM pad 117 and thebump 130 is larger (higher) than the step height SH or the sum of thethickness of the protection layer 104 and the step height SH. Throughthe formation of the metallic pad 109, the height of the bump 130 may besmaller (compared with H2) as long as the stack of the metallic pad 109,the UBM pad 117 and the bump 130 protrudes out of the opening S1 and ishigher than the barrier layer 108. In some embodiments, the total height(H4+H5+H6) of the metallic pad 109, the UBM pad 117 and the bump 130ranges from about 0.5 microns to about 1.4 microns. In some embodiments,the gap G has a size d1 (the largest distance between the bump sidewalland the barrier layer 108 located on the sidewall SS1) ranging from 0.2microns to 1.5 microns.

In alternative embodiments, FIG. 5 shows an exemplary structure obtainedby following the processes of FIG. 2A to FIG. 2F but going throughsimilar process as depicted in FIG. 1H′-1J′, so that the bondingenhancement pattern 113 has the sidewall portion 1133 but the seedpattern 115 is etched into the remained seed pattern 115 a. As shown inFIG. 5, in certain embodiments, the micron-connection structure 50includes the metallic pad 109, the UBM pad 117′, the bump 130, thepatterned insulating layer 106 and the barrier layer 108. In someembodiments, the stack of the bump 130, the UBM pad 117′ and themetallic pad 109 is located on the metallic contact 102 and electricallyconnected with the metallic contact 102. In some embodiments, the bump130 located on the UBM pad 117′ and the metallic pad 109 protrudes outof the opening S1. In some embodiments, the bump 130 sits on theremained seed pattern 115 a with the sidewall portion 1133 surroundingthe bump 130. In some embodiments, the bump 130 is surrounded andpartially shielded by the sidewall portion 1133 and the sidewall portion1133 partially covers the sidewall 130S of the bump 130. In someembodiments, in FIG. 5, the patterned insulating layer 106 includesring-shaped patterns or insulating rings 106R and the barrier layer 108conformally covers the insulating rings 106R. In FIG. 5, the ring-shapedgap G surrounding the bump 130 isolates the bump 130 from the protrudedrectangular ring 108R (the insulating rings 106R and the barrier layer108 thereon). In FIG. 5, the barrier layer 108 is not in physicalcontact with the bump 130 or the UBM pad 117′, but the barrier layer 108is in contact with the metallic pad 109. In some embodiments, the totalheight (H4+H5+H6) of the metallic pad 109, the UBM pad 117 and the bump130 ranges from about 0.5 microns to about 1.4 microns. In someembodiments, the height H7 of the sidewall portion 1133 is at leastlarger than 1/10 of and smaller than ½ of the total height (H4+H5+H6) ofthe metallic pad 109, the UBM pad 117 and the bump 130. In someembodiments, the height H4 of the metallic pad 109 is about ⅓ to ⅔ ofthe total height (H4+H5+H6) of the metallic pad 109, the UBM pad 117 andthe bump 130.

FIG. 3A to FIG. 3F are schematic cross-sectional views showing a portionof an exemplary package at various stages of the manufacturing methodfor forming at least one micro-connection structure in the packageaccording to some alternative embodiments of the present disclosure. Thesimilar or substantially the same elements as described in FIG. 1A-FIG.1K′ may be labelled with the same reference. The technology, processdetails, conditions or the materials used in the similar orsubstantially the same manufacturing process will not be repeated ordescribed in details in the following paragraphs.

Referring to FIG. 3A, in certain embodiments, the substrate 100 havingplural semiconductor chip or die 101 that includes more than onemetallic contact 102 is provided. In some embodiments, the optionalprotection layer 104, the patterned insulating layer 106, the fillinglayer are formed as described above with openings S2 exposing themetallic contact(s) 102. In some embodiments, the bonding enhancementlayer 112 and the seed layer 114 are formed sequentially on thepatterned filling layer 110, covering the opening S2 and on the metallicpad 109. In some embodiments, the bonding enhancement layer 112 isformed over the patterned filling layer 110 conformally covering theopening S2. That is, the bonding enhancement layer 112 is locateddirectly on and in direct contact with the metallic contact 102.

Referring to FIG. 3B, a masking layer 120 is formed over the substrate100 and on the seed layer 114, filling up the opening S2.

Referring to FIG. 3C, an etching back process is performed to remove themasking layer 120 outside the opening S2 and above the patterned fillinglayer 110 so that a masking pattern 121 is remained within the openingS2 with a top surface 121 a levelled with the top surface 114a of theseed layer 114.

In some embodiments, in FIG. 3D, using the masking pattern 121 as anetching mask, the seed layer 114 outside the opening S2 and above thepatterned filling layer 110 is removed to form the seed pattern 115(i.e. the seed layer 114 remained in the opening S2 and surrounding themasking pattern 121). In FIG. 3D, the bonding enhancement layer 112 isnot removed. In one embodiment, the top of the seed pattern 115 is lowerthan the barrier layer 108 located on the top surface 106 a of thepatterned insulating layer 106. In one embodiment, the seed layer 114 isremoved by performing at least a wet etching process.

Referring to FIG. 3E, the masking pattern 121 (see FIG. 3D) is removedand the seed pattern 115 located within the opening S2 is exposed.

Referring to FIG. 3F, in some embodiments, a plurality of bumps 130(only one is shown) is formed within the opening S2. In someembodiments, the material of the bumps 130 includes gold formed byelectroless plating. In certain embodiments, the bumps 130 are directlyformed on the seed pattern 115 using the gold pattern as the seed layerduring electroless plating. In some embodiments, the bumps 130 have aheight H8. In some embodiments, as the seed pattern 115 is relativelythin when compared with the bump 130 formed thereon, the seed pattern115 may be considered as part the bump 130.

Referring to FIG. 3F and FIG. 3G, the filling layer 110 and the bondingenhancement layer 112 covering the filling layer 110 are removed. Insome embodiments, the filling layer 110 is completely removed, while thebonding enhancement layer 112 is partially removed to become the bondingenhancement pattern 113. In some embodiments, the bonding enhancementpattern 113 surrounds the seed pattern 115. In some embodiments, thebonding enhancement pattern 113 has a sidewall portion 1133 covering theseed pattern 115 and a bottom portion 1135 under the seed pattern 115.That is, the remained bonding enhancement pattern 113 surrounds the seedpattern 115 and the bump 130. In one embodiment, the top of the bondingenhancement pattern 113 is lower than the barrier layer 108 on thepatterned insulating layer 106. In some embodiments, the bondingenhancement pattern 113 and the remained seed pattern 115 function as anunder bump metallurgy (UBM) pad 117. In some embodiments, the centralportion of the UBM pad 117 (the stack of the remained bondingenhancement pattern 113 and the remained seed pattern 115) has a heightH9. Due to the existence of the patterned insulating layer 106, there isa gap (empty space) G between the bump 130 and the barrier layer 108located on the sidewalls SS1. The bump 130 is separated from the barrierlayer 108 and the patterned insulating layer 106 by the ring-shaped gapG surrounding the bump 130 and the UBM pad 117. In some embodiments, thetotal height (H9+H8) of the UBM pad 117 and the bump 130 is larger(higher) than the total height of the stack of the barrier layer 108,the patterned insulating layer 106 and the protection layer 104. In someembodiments, the total height (H9+H8) of the UBM pad 117 and the bump130 ranges from about 0.5 microns to about 1.4 microns. In someembodiments, the gap G has a size d1 (the largest distance between thebump sidewall and the barrier layer 108 located on the sidewall SS1)ranging from 0.2 microns to 1.5 microns.

As the bonding enhancement layer 112 is not removed during the removalof the seed layer 114 and the bonding enhancement layer 112 is removedalong with the filling layer 110, the bump 130 is protected from theimpurities diffused from the filling layer and is able to provide aclean bonding surface, thus improving the bonding strength and thereliability of the micro-connection structure. Further, the abovemanufacturing processes are suitable for forming micro-connectionstructures in small sizes and with high density. The above-describedmicro-connection structures suitable for flip chip bonding contributefor higher bonding strength and better reliability and provide lowinductance with lower costs for fine-pitch or high density chips.

In alternative embodiments, FIG. 6 shows an exemplary micro-connectionstructure obtained following the above processes in the previousembodiments. As shown in FIG. 6, in certain embodiments, themicron-connection structure 60 at least includes the UBM pad 217, thebump 230, the insulating ring 206R and the barrier layer 208. In someembodiments, the barrier layer 208 may be formed by sputtering ordepositing a tantalum layer 207 and an aluminum layer 209 sequentiallyover the insulating ring(s) 206R and on the metallic contact 202 andthen patterned. In some embodiments, the tantalum layer has a thicknessof around 50 angstroms to about 500 angstroms. In some embodiments, thealuminum layer 209 has a thickness of around 100 angstroms to 1000angstroms. In FIG. 6, the inner sidewall and the top surface (but notcovering the outer sidewall) of the insulating ring(s) 206R of thepatterned insulating layer 206 are conformally covered by the barrierlayer 208 and the insulating ring 206R together with the barrier layer208 thereon constitute a protruded ring structure 208R. In someembodiments, the stack of the bump 230 and the UBM pad 217 is located onthe metallic contact 202 and electrically connected with the metalliccontact 202 of the substrate 200. In FIG. 6, the ring-shaped gap Gsurrounding the bump 230 isolates the bump 230 from the protrudedrectangular ring 208R. In FIG. 6, the barrier layer 208 is not inphysical contact with the bump 230 but the UBM pad 217 is locateddirectly on the barrier layer 208 above the metallic contact 202. Insome embodiments, the bump 230 located on the UBM pad 217 is higher thanthe protruded ring structure 208R and protrudes out of the opening S. Insome embodiments, the total height H10 of the UBM pad 217 and the bump230 may be equivalent to or less than 2 microns or may range from about0.5 microns to about 1.4 microns. If considering the bump 230 being around bump, the diameter (size) of the bump 230 may be equivalent to orless than 3 microns or may range from about 1.5 microns to about 2.8microns.

In some embodiments, some of the above described manufacturing processesmay be part of wafer-level packaging processes or are compatible withthe wafer-level packaging processes. In certain embodiments, themanufacturing processes of the micro-connection structures may includewafer-level bumping process or gold bumping process, involving forminggold bumps on the wafer or reconstructed wafer structure. In certainembodiments, the micro-connection structures may be applied asinter-connections for microprocessors, radio frequency ICs, imagesensors, light emitting diodes (LED), liquid crystal display (LCD),organic light emitting diode (OLED) display or other flat-panel display.

FIG. 7 is a schematic cross-sectional view of an exemplary packagehaving micro-connection structures in accordance with some embodimentsof the present disclosure. Referring to FIG. 7, a plurality ofmicro-connection structures 70 is provided between metallic contacts 702of a first substrate 700 and the contacts 810 of a second substrate 800.In some embodiments, the micro-connection structures 70 include one ormore types of micro-connection structures as described in the aboveembodiments. The substrate 700 is electrically connected with thesubstrate 800 through the micro-connection structures 70. In oneembodiment, the first substrate 700 is a semiconductor chip, such as adriver IC and the bump 730 is a gold bump or gold stud bump. In oneembodiment, the second substrate 800 is a glass substrate for a LCDdisplay and the contacts 810 are indium tin oxide (ITO) electrodes.

In some embodiments of the present disclosure, a micro-connectionstructure is provided. The micro-connection structure includes an underbump metallurgy (UBM) pad, a bump and an insulating ring. The UBM pad iselectrically connected to at least one metallic contact of a substrate.The bump is disposed on the UBM pad and electrically connected with theUBM pad. The insulating ring surrounds the bump and the UBM pad. Thebump is separate from the insulating ring with a distance and the bumpis isolated by a gap between the insulating ring and the bump.

In some embodiments of the present disclosure, a method for forming amicro-connection structure is provided. The method includes at least thefollowing steps. After providing a substrate having metallic contacts,an insulating pattern is formed over the substrate. A barrier layer isdeposited to cover the insulating pattern and over the substrate. Afilling layer is formed on the barrier layer and over the insulatingpattern. The filling layer and the barrier layer are patterned to formopenings. The openings expose the metallic contacts. A bondingenhancement layer and a seed layer are sequentially formed on thepatterned filling layer and on the exposed metallic contacts. A maskingpattern is formed within the openings. The bonding enhancement layer andthe seed layer outside the openings and on the patterned filling layerare removed. After removing the masking pattern, the seed layer locatedon sidewalls of the openings is removed to form seed patterns in theopenings. Bumps are formed on the seed patterns in the openings. Thepatterned filling layer is removed.

In some embodiments of the present disclosure, a method for forming amicro-connection structure is provided. The method includes at least thefollowing steps. A substrate having metallic contacts is provided. Aninsulating layer with first openings is formed over the substrate. Abarrier layer covering the first openings and the insulating layer isdeposited. A filling layer is deposited on the barrier layer and overthe insulating layer. Second openings exposing the metallic contacts areformed. A bonding enhancement layer and a seed layer are sequentiallyformed covering the second openings and on the exposed metalliccontacts. After filling a masking pattern in the second openings, theseed layer is removed to form seed patterns in the second openings usingthe masking pattern as an etching mask. The masking pattern is thenremoved. Bumps are formed on the seed patterns in the openings, and thebonding enhancement layer and the filling layer are then removed.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A micro-connection structure, comprising: anunder bump metallurgy (UBM) pad, electrically connected with at leastone metallic contact of a substrate, wherein the UBM pad includes afirst pattern and a second pattern, and the first pattern is disposed onand surrounded by the second pattern; a bump, disposed on the firstpattern of the UBM pad and electrically connected with the UBM pad; andan insulating ring surrounding the bump and the UBM pad, wherein thebump is separate and isolated from the insulating ring by an open trenchbetween the insulating ring and the bump.
 2. The structure of claim 1,further comprising a barrier layer covering the insulating ring, whereinthe barrier layer is in contact with the UBM pad without being incontact with the bump.
 3. The structure of claim 2, wherein the barrierlayer is in contact with the second pattern of the UBM pad without beingin contact with the first pattern of the UBM pad.
 4. The structure ofclaim 1, further comprising a metallic pad disposed directly under theUBM pad and sandwiched between the UBM pad and the at least one metalliccontact, wherein the UBM pad is electrically connected with the at leastone metallic contact through the metallic pad.
 5. The structure of claim4, wherein the second pattern of the UBM pad includes a protrudedportion surrounding the first pattern of the UBM pad.
 6. The structureof claim 5, wherein the protruded portion of the second patternsurrounds the bump and covers a sidewall of the bump, and a height ofthe protruded portion is larger than about tenth of a total height ofthe metallic pad, the UBM pad and the bump and is less than about halfof the total height of the metallic pad, the UBM pad and the bump. 7.The structure of claim 4, wherein a height of the metallic pad is aboutone third to two third of a total height of the metallic pad, the UBMpad and the bump.
 8. The structure of claim 4, wherein the barrier layeris in contact with the metallic pad without being in contact with theUBM pad and the bump.
 9. The structure of claim 1, wherein the secondpattern of the UBM pad includes a protruded portion surrounding thefirst pattern of the UBM pad.
 10. The structure of claim 9, wherein theprotruded portion of the second pattern surrounds the bump and covers asidewall of the bump, and a height of the protruded portion is largerthan about tenth of a total height of the UBM pad and the bump and isless than about half of the total height of the UBM pad and the bump.11. The structure of claim 1, wherein the first pattern of the UBM padincludes a first protruded portion, the second pattern of the UBM padincludes a second protruded portion, and the second protruded portionsurrounds the first pattern and covers the first protruded portion. 12.A micro-connection structure, comprising: an under bump metallurgy (UBM)pad, disposed on and electrically connected with at least one metalliccontact of a substrate; a bump, disposed on the UBM pad and electricallyconnected with the UBM pad; an insulating ring surrounding the bump andthe UBM pad; and a barrier layer, disposed on and covering theinsulating ring, wherein the bump is separate and isolated from thebarrier layer and the insulating ring, and the UBM pad is lower than thebarrier layer located on a top surface of the insulating ring.
 13. Thestructure of claim 12, wherein a bottom surface of the bump is in directcontact with the UBM pad.
 14. The structure of claim 13, wherein asidewall of the bump is in direct contact with the UBM pad.
 15. A methodfor forming a micro-connection structure, comprising: providing asubstrate having metallic contacts; forming an insulating pattern overthe substrate; depositing a barrier layer covering the insulatingpattern and over the substrate; forming a filling layer on the barrierlayer and over the insulating pattern; patterning the filling layer andthe barrier layer to form openings, where the openings expose themetallic contacts; forming a bonding enhancement layer and a seed layersequentially on the patterned filling layer and on the exposed metalliccontacts; forming seed patterns within the openings; forming bumps onthe seed patterns in the openings; and removing the patterned fillinglayer.
 16. The method of claim 15, wherein forming the seed patternscomprises: performing a first etching process using a masking patternwithin the openings to remove the seed layer outside the openings andlocated on the patterned filling layer; and performing a second etchingprocess to remove the seed layer located on sidewalls of the openings.17. The method of claim 16, wherein during performing the first etchingprocess, the bonding enhancement layer outside the openings and locatedon the patterned filling layer is removed.
 18. The method of claim 15,wherein forming the seed patterns comprises performing an etchingprocess using a masking pattern within the openings to remove the seedlayer located outside the openings and on the patterned filling layer.19. The method of claim 18, wherein the bonding enhancement layer isremoved during removing the patterned filling layer.
 20. The method ofclaim 15, further comprising forming metallic pads on the exposedmetallic contacts before forming the bonding enhancement layer and theseed layer.